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Biomedical subjects

P C Lefèvre

Publications and source records attributed to P C Lefèvre.

At least 19 recordsLinked to original sources
PubMed2000

Classical swine fever: the global situation.

A historical and current perspective is given of classical swine fever and its impact on pig production in different regions of the world. Data were obtained from a variety of sources including returns to the Office International des Epizooties, official government reports, other published material and local information through personal contacts. The disease has been recognized for about 170 years and efforts to control it by official intervention began in the nineteenth century. Despite this it remains a lingering problem in many parts of the world where it has both, an economic impact on swine production and a constraining effect on trade due to the measures necessary to prevent spread.

Animals↗
PubMed1996

Experience with veterinary vaccines in warm climates.

After a short description of the African laboratories manufacturing veterinary vaccines, the authors explain the main constraints for the use, in the field, of veterinary vaccines in warm climates. The need to respect the cold chain from the supplier of vaccines to the recipient animal is emphasised. In the Ivory Coast, during national vaccination campaigns, it has been proved that the quality of the rinderpest and contagious bovine pleuropneumonia vaccines is satisfactory when there is no disruption in the cold transport services. The data of this survey are exposed. In the framework of a project entitled "Thermostable rinderpest Vaccine, Transfer of Technology", a thermostable vaccine has been developed. It is manufactured in different African laboratories and integrated in some Pan African Rinderpest Campaign (PARC) vaccination programmes. On the other hand, the prospects offered by new thermotolerant attenuated vaccines against Newcastle disease are exposed. Finally, the authors present an outlook on the development of thermoresistant veterinary vaccines, such as those produced by genetic engineering, in particular with pox virus vectors.

Africa↗
PubMed1996

[Diagnosis of contagious bovine pleuropneumonia: problems and recent developments].

While it is easy to diagnose contagious bovine pleuropneumonia (CBPP) in an animal in the acute clinical stage, subacute and chronic forms are more difficult to diagnose. Recourse to laboratory tests is essential to confirm any suspicion of CBPP. As standard diagnostic procedures (isolation, culture, biochemical tests, serological tests) are lacking in specificity and sensitivity, improvements are needed. Progress in molecular biology techniques has led to new tests, among which are the polymerase chain reaction (PCR) and the enzyme-linked immunosorbent assay (ELISA) using monoclonal antibodies. Application of these techniques to CBPP offers a number of advantages, and has considerably enhanced the specificity and sensitivity of diagnosis.

Animals↗
PubMed1994

The use of monoclonal antibodies in the diagnosis of contagious caprine pleuropneumonia (CCPP).

Contagious caprine pleuropneumonia is a severe disease affecting goats in Eastern Africa and the Middle East, caused by Mycoplasma sp. type F38. Its exact geographical distribution is however not exactly known due to the lack of specificity of the available serological tests and the difficulty in cultivating M. sp. F38. A panel of monoclonal antibodies (mAbs) was produced, using crude or membrane proteins antigens from type F38 strains to immunize mice. The reactivity of the mAbs was tested by an immunobinding assay with crude mycoplasma antigens spotted on nitrocellulose filters. One hundred and twelve antigens, standardized at 0.5 mg protein/ml, were used. Mycoplasma strains were chosen among closely related species of the "mycoides cluster", M. capricolum, Group 7 of Leach, M. mycoides mycoides LC, M. mycoides mycoides SC, M. mycoides capri, as well as among species that are isolated from goat lungs, M. arginini, M. ovipneumoniae, M. putrefaciens, M. agalactiae. Out of 60 mAbs, 4 were chosen to build an identification test for mycoplasmas of the "mycoides cluster". Controls showed that accurate identification could be hampered by antigenic heterogeneity within the M. capricolum species. One mAb was used for the direct detection of M. sp. F38 antigen in pleural fluid from goats suspected of CCPP. The sensitivity of the test can be estimated at 0.5 micrograms protein/ml. Comparison with isolation results show a 74% agreement between the two methods. The same mAb was used to build a blocking ELISA. This serological test was strictly specific for CCPP. It detects antibodies in sera of naturally infected or artificially immunized animals while it remained negative with hyperimmune sera to related strains such as PG 50. Direct antigen detection and blocking ELISA are tools that may enable a better assessment of CCPP distribution.

Animals↗
PubMed1994

Cloning of the nucleocapsid protein gene of peste-des-petits-ruminants virus: relationship to other morbilliviruses.

Two independent cDNA clones, identified as representing the mRNA of the nucleocapsid protein gene of peste-des-petits-ruminants virus, were sequenced. The longest insert was 1662 nucleotides, not counting the poly(A) tail, and it was estimated that about 21 nucleotides were missing from the complete gene sequence. The sequence contained one long open reading frame encoding a protein of 525 amino acids with a predicted relative molecular mass of 58,008. Comparisons of the nucleic acid and protein sequences of all the morbillivirus nucleoproteins so far determined indicated two major subgroups in the morbillivirus genus of the Paramyxoviridae: one group included canine and phocine distemper viruses, and the other rinderpest, measles and peste-des-petits-ruminants viruses. Peste-des-petits-ruminants virus was found to be slightly more related to canine and phocine distemper viruses than were measles and rinderpest viruses.

Amino Acid Sequence↗
PubMed1993

Field diagnostic kits: a solution for developing countries?

An exact assessment of the animal health situation in a country is an essential element in formulating eradication and control programmes, and in regulating international trade in animals and animal products from that country. Due to a lack of human and technical resources, Veterinary Services in developing countries often lack precise knowledge on disease occurrence. Since the collection and transmission of reliable information on animal diseases in developing countries are major concerns of the Office International des Epizooties (OIE), a project aimed at improving this situation was implemented with international financial support. This project involved the development by the Centre for the Application of Methodology for the Diagnosis of Animal Diseases (CAMDA) of field kits for the diagnosis of the main diseases present in tropical Africa: rinderpest, peste des petits ruminants (PPR), contagious bovine pleuropneumonia (CBPP) and contagious caprine pleuropneumonia (CCPP). Several tests already exist, such as complement deoxyribonucleic acid (cDNA)-specific probes and polymerase chain reaction (PCR) for rinderpest and PPR, DNA probes and PCR for CBPP, capture enzyme-linked immunosorbent assay, the agglutination test and the immunobinding peroxidase test for CCPP, etc. With specific reference to these examples, the various problems faced by the OIE and CAMDA are reviewed.

Animals↗
PubMed1993

[Decision making in animal health].

The aim of epidemiology is to provide the necessary data to implement animal health programmes and to control the diseases. In too many occasions, especially in developing countries, informations are still incomplete and the decision is often difficult. Using the model developed by SIMON for firm management, the authors describe a decision making process calling for the personality of the decision makers when data are incomplete (limited rationality model). The different steps of the process (intelligence, design, choice, implementation and control) are discussed.

Animal Diseases↗
PubMed1992

A competitive ELISA using anti-N monoclonal antibodies for specific detection of rinderpest antibodies in cattle and small ruminants.

A competitive ELISA (C-ELISA) using monoclonal antibodies (mAbs) which bind to the nucleo-protein (NP) of rinderpest virus (RPV) for detection of RPV antibodies in cattle and small ruminant sera is described. Unlike virus neutralisation test (VNT), this test using mAb IVB2-4, can detect specific RPV antibodies without showing a cross-reaction with antibodies to peste-des-petits ruminants-virus (PPRV); by contrast, when mAb VE4-1 is used the test detects both RPV and PPRV antibodies, including low levels of antibodies that can be found in sera containing maternal antibodies. Although antibodies to the PPRV 75-1 strain are also detected with mAb 51-5-6, the test is suitable for assessing the immune status of cattle against the Rinderpest Old Kabete (RBOK) strain. The results from a panel of sera with a known status of vaccination provide evidence for a highly significant correlation between C-ELISA and VNT. This test may be a useful tool for a standardized and accurate determination of the immunity status of both cattle and small ruminants.

Animals↗
PubMed1992

Development of a species-specific DNA probe for Mycoplasma capricolum.

A specific DNA probe for the detection and identification of Mycoplasma capricolum, one of the causative agents of contagious agalactia syndrome, was selected from a genomic library. It consists of a 900bp RsaI genomic fragment of M. capricolum (reference strain), cloned into the EcoRV site of the plasmid Bluescript. By using the appropriate stringency this radiolabelled probe reacts specifically with M. capricolum when tested by dot blot hybridization against various mycoplasmal DNAs. The current level of sensitivity of the 32P-labelled 900bp RsaI probe is 500 pg of homologous DNA, corresponding to 5 x 10(4) mycoplasmas. A non radioactive labelling method, using the digoxigenin-11-dUTP, was also tested. The specificity of the digoxigenin-labelled probe was equivalent to that obtained with the radioactive probe. However the sensitivity of detection decreased to 1 ng of homologous DNA detected, corresponding to 1 x 10(5) mycoplasmas. Tests performed with milk samples have demonstrated that the radioactive 900 bp RsaI probe indeed detected M. capricolum contained in milk. A positive signal was obtained when 10(5) M. capricolum were present in the spot.

Animals↗
PubMed1992

Serological survey for bovine bacterial and viral pathogens in captive Arabian oryx (Oryx leucoryx Pallas, 1776).

Tests for antibodies to bovine bacterial and viral pathogens were conducted on 239 sera from 128 Arabian oryx (Oryx leucoryx) from seven locations (Taif, Riyadh and Mahazat as Said, Saudi Arabia; San Diego, United States of America [USA]; Shaumari, Jordan; Qatar; and Bahrain). No antibodies to Pasteurella multocida type E or epizootic haemorrhagic disease 1 virus were found. Antibodies to Brucella abortus, P. multocida type B, P. multocida type D, lumpy skin disease virus and Akabane virus were detected in 2, 1, 5, 2 and 1 animals, respectively. Evidence of P. multocida type A, Coxiella burnetti, Chlamydia psittaci and parainfluenza 3 virus was found in 3 herds (prevalence in the main herd [n = 78]: 8%), 3 herds (8%), 6 herds (7%) and 5 herds (15%), respectively. Evidence of antibodies against bluetongue virus was found in five oryx from the USA and in one oryx from the Taif herd. Antibody vaccinal titres against rinderpest virus (and the virus of peste des petits ruminants, due to cross-reactions) were found in almost all the herds. This is the first report of antibodies against B. abortus, C. burnetti, C. psittaci, parainfluenza 3 virus and Akabane virus in the genus Oryx.

Animals↗
PubMed1992

[Diagnosis of caprine contagious pleuropneumonia: recent improvements].

Due to the difficulty in isolating Mycoplasma sp. type F38, two techniques for rapid detection are proposed in order to identify the presence of mycoplasmas of the mycoides group in samples of pleural fluid. A modification in the composition of isolation media promotes the growth of type F38 mycoplasmas and inhibits the growth of M. ovipneumoniae strains.

Animals↗
PubMed1990

Peste des petits ruminants.

The peste des petits ruminants (PPR) is proving to be a disease which has an increasingly significant economic impact on a number of countries in Africa and the Middle East, and possibly also on the Indian sub-continent. The antigenic relationships which exist between the PPR and rinderpest viruses pose problems for diagnosis which complicates rinderpest control and eradication programmes. Progress has recently been made in regard to diagnosis (specific nucleic probes and monoclonal antibodies), as well as control (homologous vaccine). International legislation remains to be established and epidemiological surveys should be conducted in order to determine the exact geographical distribution of the disease.

Africa↗
PubMed1990

[Epidemiologic survey and serodiagnosis of contagious agalactia of small ruminants in Eastern Algeria].

Contagious agalactia is largely present all over the world and affects most of the African countries. It plays an important economic role in terms of subsequent milk and meat losses. One third of the 15 millions of sheep living in Algeria is present in the Eastern regions. A survey was conducted in order to confirm the existence of the disease and to evaluate the prevalence. A total of 372 sera and 80 milk samples was collected from suspected herds i.e. herds presenting either mastitis and arthritis symptoms or mastitis and keratitis symptoms. It was possible using several serological tests to detect the positive animals and to compare the specificity and sensitivity of the tests.

Algeria↗
PubMed1989

[Attenuation of a strain of rinderpest virus: potential homologous live vaccine].

Peste des petits ruminants (PPR) is a highly contagious disease of small ruminants frequently associated with severe mortality in these hosts. In countries where it occurs, PPR represents an important constraint to the improved productivity of sheep and goats. Until now the only way to combat this plague has been the use of heterologous rinderpest vaccine; all attempts to develop a homologous vaccine have ended in failure. The present communication describes the attenuation of the Nigerian strain PPRV Nig 75/1 by serial passage in Vero cells. The avirulent virus obtained has the same characteristics as Plowright and Ferris' rinderpest vaccine. The virus is advanced as a potential homologous vaccine against PPR.

Animals↗
PubMed1989

[Contagious bovine pleuropneumonia: immunoenzymatic test and kinetics of antibody formation in experimental infection. Relation of complement fixation, excretion and the study of circulating antigen].

An experimental reproduction of CBPP was implemented and the animals were surveyed for serology during 4 months. The ELISA/IgG test detects the antibodies few days after the CF test but is more precise for detection on the longer term. The early antibody detection can be done with the ELISA/IgM test. Circulating antigen (galactan) has been detected in a cow that died of an acute form of CBPP. Excretion of mycoplasmas starts 1 to 2 weeks before the seroconversion: the ELISA/IgG test remains positive during the excretion phase and even longer.

Animals↗